M5

M5 is one of the oldest and largest globular clusters known, located about 24,500 light-years away in the constellation Serpens Caput. It is estimated to be 13 billion years old and contains over 100,000 stars in a sphere about 165 light-years across. The cluster has a bright, dense core surrounded by a beautiful halo of resolved stars.

Located about 20 arcminutes north-northwest of the star 5 Serpentis. Visible to the naked eye under very dark skies as a faint star. Binoculars show a bright, round fuzzy patch. A 4-inch telescope begins resolving stars at the edges, while an 8-inch at 150x provides a spectacular view with stars resolved across much of the cluster. Often compared favorably to M13. Best observed from May through August.

Discovered by Gottfried Kirch in 1702 while observing a comet. Charles Messier found it independently in 1764, describing it as a round nebula. William Herschel resolved it into stars in 1791, counting '200 stars and more.'